1. POS1POS2 IL-2IL-4 IL-5IL-6 IL-8IL-10 IL-13GM-CSF IFN γ TNF α A B C Standard 1 Standard 2 Standard 3 Standard 4 Standard 5 Standard 6 Standard 7 CNTRL MCF10A Mock MCF10A Mock MCF10A Gα12QL MCF10A Gα12QL MDA-MB- 231 Mock MDA-MB- 231 Mock MDA-MB- 231 Gα12QL MDA-MB- 231 Gα12QL Supplementary Figure S1. Human TH1/TH2 array 1. (A) A full Quantibody protein array (RayBiotech) analysis was conducted to profile interleukin and cytokine secretion from breast cancer cells transfected with control or Gα12QL vectors. (B) Layout of proteins represented in each section by their corresponding antibodies. (C) Experimental layout of samples. See the legend to Fig. 3 and Materials and Methods for experimental details.

2. POS1POS2 MMP-1MMP-2 MMP-3MMP-8 MMP-9MMP-10 MMP-13TIMP-1 TIMP-2TIMP-4 Supplementary Figure S2. Human MMP array 1. (A) Original full Quantibody protein array (RayBiotech) analysis was conducted to profile MMP from breast cancer cells transfected with control or Gα12QL vectors. (B) Layout of proteins represented in each section by their corresponding antibodies. (C) Experimental layout of samples. See the legend to Fig. 3 and Materials and Methods for experimental details. A BC CNTRL Standard 6 Standard 4 Standard 2 MCF10A Mock scRNA MCF10A Mock siMMP-2 MCF10A Mock siMMP-9 MCF10A Gα12QL scRNA MCF10A Gα12QL siMMP-2 MCF10A Gα12QL siMMP-9 MDA-MB- 231 Mock scRNA MDA-MB- 231 Mock siMMP-2 MDA-MB- 231 Mock siMMP-9 MDA-MB- 231 Gα12QL scRNA MDA-MB- 231 Gα12QL siMMP-2 MDA-MB- 231 Gα12QL siMMP-9

3. POS1POS2BLC EotaxinEotaxin-2G-CSF GM-CSFI-309ICAM-1 IFNγIL-1αIL-1β IL-1raIL-2IL-4 IL-5IL-6IL-6sR IL-7IL-8IL-10 IL-11IL-12p40IL-12p70 IL-13IL-15IL-16 IL-17MCP-1MCSF MIGMIP-1αMIP-1β MIP-1δPDGF-BBRANTES TIMP-1TIMP-2TNFα TNFβTNF RITNF RII A B C Supplementary Figure S3. Human inflammation array 3. (A) A full Quantibody protein array (RayBiotech) analysis was conducted to miscellaneous cytokine secretion from breast cancer cells transfected with control or Gα12QL vectors. (B) Layout of proteins represented in each section by their corresponding antibodies. (C) Experimental layout of samples. See the legend to Fig. 3 and Materials and Methods for experimental details. CNTRL Standard 6 Standard 4 Standard 2 MCF10A Mock scRNA MCF10A Mock siMMP-2 MCF10A Mock siMMP-9 MCF10A Gα12QL scRNA MCF10A Gα12QL siMMP-2 MCF10A Gα12QL siMMP-9 MDA-MB- 231 Mock scRNA MDA-MB- 231 Mock siMMP-2 MDA-MB- 231 Mock siMMP-9 MDA-MB- 231 Gα12QL scRNA MDA-MB- 231 Gα12QL siMMP-2 MDA-MB- 231 Gα12QL siMMP-9

4. Supplementary Figure S4. Expression of dominant active Gα12 in MCF10A cells induces secretion of cytokines IL-6 and IL- 8, and MMP-2. (A) Protein array analysis of factors present in conditioned media. MCF10A cells were transfected either with control vector (Mock) or Gα12QL as indicated. Following a 72h incubation, media was harvested and subject to antibody-based arrays; see Materials and Methods for details. (B). Quantification of relative densities of dots representing IL-6, IL-8 and MMP-2 in quadruplicates using TotaLab 2.0 program. Results were obtained from 3 chip-arrays each having two replicas of conditioned media. Bars represent the mean ± S.E. of quadruplicate determinations; * (p < 0.05). Mock G α 12QL IL-6 IL-8 Human Inflammation Array-3 Human MMP Array-1 MMP-2 ABAB

5. A C B MMP-2 Supplementary Figure S5. Validation of increased secretion of IL-8 and MMP-2 expression of MCF10A cells expressing dominant activate Gα12. (A) Expression of IL-8 in total cell lysates of MCF10A cells transfected with either mock (M) vector or Gα12QL (QL) vector. (B) MMP-2 levels in conditioned media of MCF10A cells transfected with either mock (M) vector or Gα12QL (QL) vector. (C) Zymography analysis of gelatinase activity of MMP-2 in conditioned media of MCF10A cells transfected with either mock (M) vector or Gα12QL (QL) vector. Experimental conditions are as in (B). In the center panel, aliquots of conditioned media from were analyzed by silver-as the loading controls. Data in the lower panel are the are the mean ± S.E. of quadruplicate determinations from a single experiment that is representative of two independent experiments. MMP-2 Silver stained gels (loading control)

6. Supplementary Figure S6. Analysis of MMP-2 activity upon Gα12QL expression by in-situ zymography. Secreted gelatinase activity in living MDA-MB-231 cells transfected with either mock or Gα12QL expression vectors is seen as the darkened areas. The corresponding lack of dark areas upon MMP-2 knockdown (siMMP) is also observed. The lower panel shows a quantitation of the relative gelatinase activity of all samples. Data represents the means +/- S.D. of triplicate determinations for a single experiment, which is representative of two such experiments. scRNA siMMP-2 Gα12QL Mock 100 200 300 Gelatinase activity (% control)

7. Supplemental Figure S7. Interleukins and MMP-2 are involved in Gα12-mediated invasion of MCF10A cells. MCF10A cells were transfected with either control vector (Mock) or Gα12QL vectors as indicated, in addition, for (B) the cells were co-transfected with either scrambled (scRNA) or MMP-2 siRNA; the plasmid vectors also expressed GFP. The green cells were then sorted, and the enriched fractions subject to invasion assays (A) Addition of IL-6 and IL-8 specific antibodies resulted in reduced Gα12-stimulated cell invasion. Data is pooled from three independent experiments, each involving triplicate determinations. Bars represent the mean ± S.E. (B) Depletion of MMP-2 with specific siRNA decreases Gα12-stimulated invasion of MCF10A cells. Data is pooled from three independent experiments, each involving duplicate determinations. For both panels, bars represent the mean ± S.E.; * (p < 0.05). A B

8. IL-8 IL-6 MMP-2 NF-kB Oct1 AP-1 NF-kB NF-kB TATA -1282 -580 -470 -395 -71 -35 AP-1 NF-kB CRE NF-kB GATA NF-kB TATA -1200 -900 -330 -320 -114 -80 -70 -25 NF-kB IRF HNF AP-1 NF-kB TATA -1482 -580 -420 -370 -120 -90 -70 -12 Supplementary Figure 8. Schematic representation of the transcription factor binding sites present in the the 5’ UTRs of the IL-6, IL-8, MMP-2 and MMP-9 promoters. Predicted binding sites for transcription factors on promoter regions of IL-6, IL-8 and MMP-2 genes are shown.